Initially, the carrier agreed to a £5.2 billion takeover by Castlelake but just days later it accepted a £5.7 billion takeover proposal from US investor Apollo.
The company, which agreed a deal to acquire Trafalgar, Contiki and Uniworld parent The Travel Corporation in 2024, upped the ante with an offer worth £7.15 per share.
Castlelake originally had until 5pm on Monday (3 August) to make a formal offer or walk away, while Apollo had until the same time on Friday (7 August) to make its proposal official.
